This is an area that’s been bugging me since day 1. The main gear doors a attached to the gear legs. But the nose doors are hinged. They are brought up by means of a rather complicated hydraulic system. Here’s a picture of a completed plane.

This picture is looking aft at the canard bulkhead. The greenish looking pipe going down is the nose gear leg. The opening at the bottom is the space that the nose gear comes through when it retracts. You can see the rear hinge arms of the nose gear doors (they’re white). Those doors are closed by a hydraulic cylinder (gold at the top center partially behind the large red flexible duct) which pulls up on a pair of arms that extend down to the door hinges. The hydraulic cylinder is activated by a switch (off to the right near the bottom of the cylinder) that gets triggered when the nose gear is up.

I’ve seen a couple other builders that used this method. After some investigation, I found the guy who builds these.

I asked the builder who came up with this if he could build one for me. But his fabrication guy was unavailable. So Malcolm told me he had built one that it’s in a plane nearby. A call to Terry Miles had me stopping by to take some pictures and measurements.

Same view as the previous picture but with the Hangar 18 mechanism.

The spring is so that when the gear bounces a little while in the up position, the doors will stay closed.

Some fabrication I can do. But I’m not a welder and I don’t have a milling machine. So Lynn, my current A&P put me touch with a guy who put me in touch with a guy who does metal work. I sent him my drawings and measurements. In return, he sent me:

Here are those parts installed.

Now I have to get the linkage and spring so I can drill for the pins to fix the arms in place.

Starting the plumbing for the landing gear. Before any lines are run, the emergency dump valve has to be mounted. The dump valve allows the landing gear to be lowered in the event of a loss of electrical power. In the Cessna, this is accomplished with a manual pump. If the hydraulic pump can’t be run, the gear is pumped down manually. On the Velocity, the gear is retracted with hydraulic pressure. When the pressure is released, gravity will pull the gear down. Simple!

Originally, the dump valve was on the pilot side of the center keel. But a while back, it was moved to the co-pilot side. Malcolm has a set of templates to identify the shape and size of the opening for the dump valve.

First the location of the valve is determined. Then the first template is placed and the hole is marked.

Then the first hole is cut and the other templates are placed and marked.

The outer skin and foam are cut away.

Then the foam gets a radius.

Finally, the area is covered with two layers of BID.

The bulkhead fittings for the hydraulic lines will be located as high on the bulkhead as possible. To identify the optimal location, Malcolm shined a light from the inside of the keel towards the canard bulkhead. Then I marked the canard bulkhead so we could see where the fittings would be located.

Then, two holes where drilled.

And the bulkhead fittings are installed.

Once the 2 BID layup has cured, the dump valve is installed.

Now that the bulkhead fittings and the dump valve is installed, it’s time to finish up the landing gear hard line plumbing.

The lines from the bulkhead going aft inside the keel.

Between the bulkhead and the dump valve is the nose gear overcenter stop. So the hard lines have to be bent around that.

The lines aft of the dump valve and the T on the other line will be high-pressure flex lines.

Forward of the canard bulkhead, the line will go from the bulkhead fittings to the hydraulic pump.

At Hangar 18, they take the “Working isn’t good enough. It also has to look good and be aesthetically pleasing to the eye.” approach. The way Malcolm ran these lines is almost a work of art.

With the landing gear hydraulic hard lines installed, there are two flex lines which go from the dump valve T fittings to the nose gear cylinder. The two flex lines from the main cylinder to the nose cylinder were run in Sebastian.

I am using a pre-wired landing gear control unit made by Wayne Lanza at Composite Designs. It consists of a control unit and and gear select lever. The control unit is mounted in the nose of the fuselage.

First, hardpoints are created, attached to the control unit and then structural adhesive is applied to the back of the hardpoints. The control unit is held in place while the adhesive cures.

When you’re done trimming and mounting the door, it looks like this at the top when the gear is up (Keep in mind that the airplane is upside down).

That big honkin’ gap is there because when the gear comes down, the door would hit the fuselage and prevent the gear from fully extending if it was any longer. I guess the theory is no one will notice it’s there when the gear is down and the only time the gear will be up is where it’s in flight. But I’d know it’s there.

A couple emails to Malcolm revealed that earlier Velocities had a small door that will cover the opening. And I COULD have saved the extra door material to use as a small door to cover the opening. But I couldn’t do that because I used the “sneak up on it” approach when I located the final position of the cut.

So I covered the side of the fuselage next to the gear door and laid out a few layers of triax and BID (so it would match the curvature of the fuselage). Then I cut it to fill the opening. To accomplish this, I used the tape-it-to-the-outside-and-shine-a-light-from-the-inside to locate where to cut.

Then I cut and drilled a pair of hinges and did a dry fit.

Yep, it moves.

I riveted the hinge to the mini-door and put nutplates on the side that would mount to the fuselage.

Next I beveled the edge and built a flange so it would fit with the door.

Here’s how looks all installed and operational.

This is one of those milestones that makes all the days of seemingly no progress worthwhile.

It’s a rather large file but (for me) it’s worth it.

Gear Retract

Or you can view it here on YouTube.

I omitted a rather important point in the previous post on gear retraction. Which is after the gear was raised, it didn’t stay up. As soon as the power was removed, the gear began dropping. It is supposed to stay up.

The culprit was a bad (leaking) nose gear cylinder. A call to Albert revealed that there was a bad batch of these. I called Scott Swing at the factory and he confirmed it. The date that I got mine was at the tail end of when those cylinders were in the pipeline. He said to send it back and he would rebuild it.

So I removed the cylinder and shipped it down to Sebastian, FL. Scott rebuilt it and the cylinder got back to Malcolm’s about a week later (when I wasn’t there). So Malcolm reinstalled it and did another test.

This time, after the gear was retracted and the power removed, the gear stayed up. Malcolm said that FORTY-EIGHT HOURS LATER, the landing gear was still firmly up.